Rotary trencher having a vertical axis of rotation

ABSTRACT

A trimming apparatus for open longitudinal trenches of the type used in irrigation canal and distribution systems. The trimmer utilizes a vertical cutter assembly having a plurality of identical equiangularly oriented radial blades which move in a path defining an inverted truncated cone. Immediately rearward of the cutter assembly is a moldboard assembly having cutter edges for engaging the loosened soil and longitudinal shoes for smoothing the resulting trench surfaces. The moldboard assembly vertically supports the apparatus to permit accurate grade control. Material is removed through an aperture in the center of the moldboard assembly and is conveyed to the side of the trench by elevating conveyors.

United States Oct. 23, 1973 ROTARY RENcnER HAVING A VERTICAL AXIS 0F ROTATION [75] Inventors: Raymond A. Hanson; Robert L.

Roller, Spokane, Wash.

[73] Assignee: R. A. Hanson Company, Inc.,

Spokane, Wash.

[22] Filed: Aug. 24, 1972 [21] App]. No.: 283,478

FOREIGN PATENTS OR APPLICATIONS Germany 37/91 Primary Examiner-Edgar S. Burr Assistant ExaminerClifford D. Crowder Attorney-Greek Wells et al.

[57] ABSTRACT A trimming apparatus for open longitudinal trenches of the type used in irrigation canal and distribution systems. The trimmer utilizes a vertical cutter assembly having a plurality of identical equiangularly oriented radial blades which move in a path defining an inverted truncated cone. Immediately rearward of the cutter assembly is a moldboard assembly having cutter edges for engaging the loosened soil and longitudinal shoes for smoothing the resulting trench surfaces. The moldboard assembly vertically supports the apparatus to permit accurate grade control. Material is removed through an aperture in the center of the moldboard assembly and is conveyed to the side of the trench by elevating conveyors.

5 Claims, 4 Drawing Figures Patented Oct. 23, 1973 2 Sheets-Sheet 1 Patented Oct. 23, 1973 3,766,672

2 Sheets-Sheet- 2 BACKGROUND or THE INVENTION This invention basically relates to devices for forming longitudinal trenches by an element that rotates about a vertical axis as itis being moved longitudinally. An early example of such a device, using a spiral auger cutter element is the Hanneborg U.S. Pat. No. 706,175. Another early machine for forming ditches is the Wheaton U.S. Pat. No. 689,947. A more recent example of devices of this type is the Smith U.S. Pat. No. 3,383,783. Other patents of interest are the patents to Roehr, Smith, U.S. Pat. No. 3,257,662 and Chris tensen, U.S. Pat. No. 1,171,771.

The above patents make primary use of the rotary elements for lifting material from the trench. While they do show auxiliary conveyors or guide surfaces adjacent to an auger, it is theauger that does most of the lifting, requiring considerable power at the auger and resulting in considerable wear of the auger elements. Furthermore, the support for the illustrated augers appears to be entirely-in the supporting tractor or framework. In contrast, the present apparatus is supported within the trench as it is formed, the device being freely pivotable relative to the tractor. about a transverse hitch axis. Thispermits the apparatus to float slightly to clear an obstruction when necessary. It also allows the operator to more accurately gauge and control the grade of the trench, since the operation of the trench digging apparatus is independent of the momentary elevation of the ground supported tracks.

' SUMMARY OF THE INVENTION The basic invention comprises a ground-supported frame, together with a rotatable cutter assembly mounted about a vertical axis on the frame. The cutter assembly includes equiangularly spaced radial blades rotatably mounted to the frame about the vertical axis. The outwardly facing edge of each blade generates the desired cross-sectional configuration of the trench in a transverse plane containing the axis. A transverse moldboard assembly is fixed to the frame immediately rearward of the path of the radial blade edges. The moldboard has blades including cutter edges oriented longitudinally coincident with cross-sectional configuration generated by the radial blade edges. The center of the moldboard has an open aperture and a conveyor is located on the frame rearward of the aperture to receive material.

It is a first object of this invention to provide a vertical shaft trimmer using radial blades which can be readily fabricated without generating a spiral or auger, I

and which need not be used primarily as a lifting device I for loosened soil.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view showing the trimmer in operation, with the soil and trench surfaces shown in vertical elevation;

FIG. 2 is an enlarged vertical sectional view of the trimming structure taken along its longitudinal center plane;

FIG. 3 is a l; and

FIG. 4 is a rear view of the structure shown in FIG. 1.

top view of the apparatus shown in FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENT This disclosure relates to a device for cutting and trimming an open longitudinal trench. Such trenches are used for irrigation purposes, and are often lined with concrete to exacting specifications with respect to grade, slope, and quality of the soil surfaces within the trench. Prior trimmers of the rotary type have been reasonably crude in surface treatment within the trench. Emphasis has been placed primarily in facilitating removal of the material by an auger rather than on the resulting trench surface quality.

One obvious problem of prior attempts to use an auger as a rotating cutter is the fact that the action of the auger in rotating about a vertical axis tends to pull the apparatus downwardly as it liftssoil. This creates vertical thrust forces which must be counteracted by the surface support equipment. In the present apparatus no such thrust forces aredeveloped, and additional 7 longitudinal surfaces are provided in a trimming moldboard assembly to maintain the trimming and cutting apparatus at a controlled elevation. This elevation can be accurately controlled by reference to a grade control string or other reference control assembly.

The trimming apparatus illustrated is carried by a rigid upper frame 10. Immediately beneath frame 10 is a rotatable cutteras'sembly 11 followed by a rearwardly adjacent moldboard assembly 12.. The moldboard assembly 12 is fixed to frame 10 and vertically supports frame 10 across the width of the resulting trench. The frame 10 is mounted to a tractor 13 which pulls the frame and the cutter and moldboard assemblies to the left as seen in FIGS. 1 and 3. 'A connecting hitch apparatus is generally shown at 14.

The tractor 13 can be either a conventional tractor of common manufacture or a special purpose vehicle designed for trailing the apparatus. As illustrated, control console 15 is located at the rear of the tractor for permitting manual inspection of operation of the trimmer and automatic grade and steering controls when desired. Such controls are well-developed in this area of grading and trenching, and typically are referenced from a string line or lines extending alongside the desired path of the trench. Such controls typically monitor grade, steering and cross-leveling of the trimmer assembly.

At the rear of tractor 13 is a vertical support post 17 which slidably and pivotally mounts a support collar 18 having a rearwardly protruding pivot tongue 20 extending from it. The rear portion of tongue 20 is transversely pivoted to the front end of frame 10 by a pivot shaft shown at 21.

The cutter assembly 11 can be best understood from a study of FIG. 2. It basically comprises a plurality of radial blades 22. Six such blades are shown in the illustrated structure, forming a hexagon pattern when viewed from the top (FIG. 3). Blades 22 are joined to a central hub by spider arms 23 and their outer extremities are joined by upper horizontal braces 24 arranged in a hexagonal pattern. The outer radial edges of blades 22 are provided with tangential digging teeth. The lowermost portion of each blade has an extended continuous digging tooth 25 followed by discontinued teeth 26 spaced from one another along the height of the blade. These tangential teeth 25, 26 serve to loosen soil prior to engagement by the radial surfaces of blades 22.

The blades 22 are mounted to the lower end of the vertical drive shaft 27 centered about a vertical axis on frame 10. The shaft 27 is rotatably mounted to the frame by bearing assembly 28. Its upper end has a driven sprocket 30 fixed to it, powered by a motor 33 on frame 10 through an intermediate drive sprocket 32 and chain 31.

Immediately rearward of the cutter assembly 11 is the moldboard assembly 12. The purpose of the moldboard assembly 12 is to engage the soil loosened by the rotary cutter assembly 11 and to partially lift this soil for reception onto receiving conveyors. In addition, the moldboard assembly trims and smooths the side surfaces of the trench and further serves as an elevational support for frame 10. In fact, the entire assembly rests on the longitudinal surfaces of the moldboard assembly 12, since it is otherwise freely pivotable about the previously described transverse pivot shaft 21.

As the radial blades 22 are rotated about the vertical axis of shaft 27, their outwardly facing edges, which are located identically relative to the axis of shaft 27, generate the desired cross-sectional configuration of the trench in a transverse plane containing that axis. The moldboard assembly 12 follows the rotating cutter assembly l1 and includes cutter edges which are oriented longitudinally coincident with the cross-sectional configuration generated by the radial blade edges in this transverse plane. These blade edges are presented by lower horizontal blades 34 and side blades 35 which are mirror images of one another. The cutter edges of blades 34, 35 are respectively designated in the drawings by the numerals 54, 55.

Immediately rearward of the edges 54, 55 are longitudinal shoes 36, 37 which slide along the formed trench surfaces and smooth the soil surfaces to an accurate consolidated condition. The shoes 36, 37 are relatively wide and these surfaces serve as the elevational support surfaces for the trimmer assembly within the trench.

The forwardly facing area bounded by blades 34, 35 is substantially solid to control the soil loosened due to action of the cutter assembly 11. A center plate 38 extends upwardly and rearwardly from the lower horizontal blade 34. It contains an aperture 43 formed therethrough, permitting passage of soil materials rearwardly through the moldboard assembly 12. The center plate 38 is joined at each side by side plates 40 which extend upwardly and rearwardly from the respective side blades 35. It is to be noted from the drawings that the edges 55 join the respective ends of edge 54 and are both inclined rearwardly and diverge upwardly along their respective lengths.

The wing-shaped moldboard assembly 12 is reinforced by upright rear. beams 41 which are rigidly secured to the rear end of frame 10. The beams 41 serve as longitudinal braces along the height of the moldboard assembly 12, and include inwardly facing surfaces 42 at the respective sides of aperture 43. The surfaces 42 serve a second purpose in confining soil materials passed through aperture 43 and deposited upon a receiving conveyor belt 44. The moldboard assembly 12 is further braced by diagonal wing braces 51 which extend between frame 10 and the outer ends of the assembly 12, and by triangular brace plates 52 fixed to frame 10 at the upper end of the moldboard assembly (FIG. 3).

Material received through aperture 43 and deposited on the conveyor belt 44 is moved upwardly by movement of belt 44 and deposited onto a discharge belt 46 directed to one side of the resulting trench. An arcuate deflector 45 is mounted to frame 10 to insure accurate deposit of material on the belt 46. The conveyor assembly for belt 46 is elevationally supported by an upstanding mast 47 on frame 10, and a connecting length of cable 50. Its lower end is pivotally carried on frame 10 by a support assembly shown at 48.

In operation, the cutter assembly 11 is constantly rotated as the tractor 13 moves to the left in FIGS. 1 and 3. The rotation of the radial blades 22 and projecting teeth 25, 26 loosens the soil, opening a rough trench having a trapezoidal configuration with the base more narrow than the top. This cutting action is immediately followed by passage of the moldboard assembly 12, which performs a final trim action due to the downwardly and forwardly directed blades 34, 35. All loose soil within the confines of edges 54, are urged toward the center of the moldboard assembly 12 during forward travel of the apparatus through the soil, where the soil passes through aperture 43 and is then deposited at the side of the trench. In addition, the side and bottom surfaces of the trench are smoothed by the sliding action of shoes 36, 37, which iron the soil and exert considerable downward pressure due to the weight of the assembly pivoted about the shaft 21.

The longitudinal nature of shoes 36, 37 prevents the cutter assembly 11 and moldboard assembly 12 from digging below the height set by adjustment of collar 18 along the height of post 17. Because the shoes 36, 37 are aligned along the longitudinal path of movement of the machine and the blades 22 are radial, there is no resulting negative draft, as would be the case if the inclined blades 34, 35 were used alone or were an auger to be used. The combination of the moldboard assembly and pressing shoes 36, 37 permits one to accurately control the depth of cut of the apparatus by controlling the working elevation of the collar 18 relative to the tractor 13. This control can be accomplished either manually or by automatic referencing to an external guide, such as a fixed string line.

The apparatus lends itself particularly to small scale irrigation trenches and the like, which are often formed in reasonably loose soil that can be readily trimmed by the type of cutter shown. The apparatus has substantial capability for moving large quantities of soil from the trench and completes the production of a finished trench surface suitable for lining by concrete or other lining materials.

Modifications might appear to one skilled in the art, and for this reason, this disclosure is not to be limited except as set out in the following claims.

Having thus described our invention, we claim:

1. In a trimmer foropen trenches of constant crosssectional configuration centeredalong a predetermined path:

a ground-supported frame having a vertical axis thereon; 5

a rotatable cutter assembly comprising a plurality of equiangularly spaced radial blades rotatably mounted about said axis, each having an outwardly facing edge located identically relative to said axis and generating the desired cross-sectional configuration of the trench in a transverse plane containing said axis when the blades are rotated about said axis;

a transverse moldboard assembly fixed to the frame rearwardly adjacent to the rotational path of the radial blade edges, said moldboard having outer fixed blades including cutter edges oriented longitudinally coincident with the cross-sectional configuration generated by the radial blade edges in said transverse plane;

the center of said moldboard having an open aperture formed therethrough to permit rearward passage of material through the moldboard;

and conveying means on said frame at a location rearward of said aperture to receive material passed through said aperture.

2. The apparatus set out in claim 1 wherein said moldboard assembly further comprises:

rearwardly extending shoes located longitudinally back of the blade cutter edges and having outer surfaces longitudinally coincident therewith for smoothing the trench surfaces after passage of the cutter edges.

3. The apparatus as set out in claim 1 wherein said cutter assembly is in the shape of an inverted truncated cone;

said moldboard assembly including a central lower horizontal blade cutter edge longitudinally coincident with the lower surface of the cone and angularly inclined side blade cutter edges coincident with the sides of the cone.

4. The apparatus as set out in claim 3 wherein the side blade edges are inclined rearwardly from bottom to top.

5. The apparatus as set out in claim 4 wherein the moldboard assembly includes a forwardly facing center plate inclined upwardly and rearwardly from the central lower horizontal blade and containing said aperture, said center plate being joined to said plates extending between its respective side edges and the side blades. 

1. In a trimmer for open trenches of constant cross-sectional configuration centered along a predetermined path: a ground-supported frame having a vertical axis thereon; a rotatable cutter assembly comprising a plurality of equiangularly spaced radial blades rotatably mounted about said axis, each having an outwardly facing edge located identically relative to said axis and generating the desired crosssectional configuration of the trench in a transverse plane containing said axis when the blades are rotated about said axis; a transverse moldboard assembly fixed to the frame rearwardly adjacent to the rotational path of the radial blade edges, said moldboard having outer fixed blades including cutter edges oriented longitudinally coincident with the cross-sectional configuration generated by the radial blade edges in said transverse plane; the center of said moldboard having an open aperture formed therethrough to permit rearward passage of material through the moldboard; and conveying means on said frame at a location rearward of said aperture to receive material passed through said aperture.
 2. The apparatus set out in claim 1 wherein said moldboard assembly further comprises: rearwardly extending shoes located longitudinally back of the blade cutter edges and having outer surfaces longitudinally coincident therewith for smoothing the trench surfaces after passaGe of the cutter edges.
 3. The apparatus as set out in claim 1 wherein said cutter assembly is in the shape of an inverted truncated cone; said moldboard assembly including a central lower horizontal blade cutter edge longitudinally coincident with the lower surface of the cone and angularly inclined side blade cutter edges coincident with the sides of the cone.
 4. The apparatus as set out in claim 3 wherein the side blade edges are inclined rearwardly from bottom to top.
 5. The apparatus as set out in claim 4 wherein the moldboard assembly includes a forwardly facing center plate inclined upwardly and rearwardly from the central lower horizontal blade and containing said aperture, said center plate being joined to said plates extending between its respective side edges and the side blades. 